Media mills have long been used in the milling of pigments for finishes. Such mills can be used to grind such materials, but more typically, act to deagglomerate or disperse the material in a liquid carrier.
A media mill typically comprises a container housing a particulate grinding media and a rotatable agitator. The agitator generally has a central shaft onto which are mounted discs or projections which aid in producing shear. The product to be milled, typically a powder in a carrier fluid, is introduced into the mill so as to flow from one end to the other. In a vertical mill, the flow is generally from bottom to top. As the product flows through the grinding media, the combination of the flow and the rotation of the agitator causes the media to become suspended or fluidized in the product. The flow difference, or shear, between the grinding media and the product deagglomerates or disperses the material being processed in the mill.
It would be desirable to improve the efficiency and/or quality of milling, for example, through reduced processing times or increased flow, or the production of finer particle dispersions.